/*

 * reserved comment block

 * DO NOT REMOVE OR ALTER!

 */

/**

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements. See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership. The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License. You may obtain a copy of the License at

 *

 * http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing,

 * software distributed under the License is distributed on an

 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

 * KIND, either express or implied. See the License for the

 * specific language governing permissions and limitations

 * under the License.

 */

package com.sun.org.apache.xml.internal.security.utils.resolver.implementations;

import com.sun.org.apache.xml.internal.security.signature.XMLSignatureInput;

import com.sun.org.apache.xml.internal.security.utils.XMLUtils;

import com.sun.org.apache.xml.internal.security.utils.resolver.ResourceResolverContext;

import com.sun.org.apache.xml.internal.security.utils.resolver.ResourceResolverException;

import com.sun.org.apache.xml.internal.security.utils.resolver.ResourceResolverSpi;

import org.w3c.dom.Document;

import org.w3c.dom.Element;

import org.w3c.dom.Node;

/**

 * This resolver is used for resolving same-document URIs like URI="" of URI="#id".

 *

 * @see <A HREF="http://www.w3.org/TR/xmldsig-core/#sec-ReferenceProcessingModel">The Reference processing model in the XML Signature spec</A>

 * @see <A HREF="http://www.w3.org/TR/xmldsig-core/#sec-Same-Document">Same-Document URI-References in the XML Signature spec</A>

 * @see <A HREF="http://www.ietf.org/rfc/rfc2396.txt">Section 4.2 of RFC 2396</A>

 */

public class ResolverFragment extends ResourceResolverSpi {

    private static final com.sun.org.slf4j.internal.Logger LOG =

        com.sun.org.slf4j.internal.LoggerFactory.getLogger(ResolverFragment.class);

    @Override

    public boolean engineIsThreadSafe() {

        return true;

    }

    /**

     * {@inheritDoc}

     */

    @Override

    public XMLSignatureInput engineResolveURI(ResourceResolverContext context)

        throws ResourceResolverException {

        Document doc = context.attr.getOwnerElement().getOwnerDocument();

        Node selectedElem = null;

        if (context.uriToResolve.equals("")) {

            /*

             * Identifies the node-set (minus any comment nodes) of the XML

             * resource containing the signature

             */

            LOG.debug("ResolverFragment with empty URI (means complete document)");

            selectedElem = doc;

        } else {

            /*

             * URI="#chapter1"

             * Identifies a node-set containing the element with ID attribute

             * value 'chapter1' of the XML resource containing the signature.

             * XML Signature (and its applications) modify this node-set to

             * include the element plus all descendants including namespaces and

             * attributes -- but not comments.

             */

            String id = context.uriToResolve.substring(1);

            selectedElem = doc.getElementById(id);

            if (selectedElem == null) {

                Object exArgs[] = { id };

                throw new ResourceResolverException(

                    "signature.Verification.MissingID", exArgs, context.uriToResolve, context.baseUri

                );

            }

            if (context.secureValidation) {

                Element start = context.attr.getOwnerDocument().getDocumentElement();

                if (!XMLUtils.protectAgainstWrappingAttack(start, id)) {

                    Object exArgs[] = { id };

                    throw new ResourceResolverException(

                        "signature.Verification.MultipleIDs", exArgs, context.uriToResolve, context.baseUri

                    );

                }

            }

            LOG.debug(

                "Try to catch an Element with ID {} and Element was {}", id, selectedElem

            );

        }

        XMLSignatureInput result = new XMLSignatureInput(selectedElem);

        result.setSecureValidation(context.secureValidation);

        result.setExcludeComments(true);

        result.setMIMEType("text/xml");

        if (context.baseUri != null && context.baseUri.length() > 0) {

            result.setSourceURI(context.baseUri.concat(context.uriToResolve));

        } else {

            result.setSourceURI(context.uriToResolve);

        }

        return result;

    }

    /**

     * Method engineCanResolve

     * {@inheritDoc}

     * @param context

     */

    public boolean engineCanResolveURI(ResourceResolverContext context) {

        if (context.uriToResolve == null) {

            LOG.debug("Quick fail for null uri");

            return false;

        }

        if (context.uriToResolve.equals("") ||

            context.uriToResolve.charAt(0) == '#' && !context.uriToResolve.startsWith("#xpointer(")

        ) {

            LOG.debug("State I can resolve reference: \"{}\"", context.uriToResolve);

            return true;

        }

        LOG.debug("Do not seem to be able to resolve reference: \"{}\"", context.uriToResolve);

        return false;

    }

}